Shuxian Meng

Double-N doping: a new discovery about N-doped TiO2 applied in dye-sensitized solar cells

In this paper, we first investigated the optimal amount of ammonia to add, using ammonia as the single dopant for use in dye-sensitized solar cells (DSSCs). Using this optimal amount of ammonia, urea was introduced as the second N dopant. The DSSCs produced by double-N doped samples combine the advantages of increased visible light absorption with ammonia as the nitrogen dopant and enlarged interface area with urea as the second nitrogen dopant. Not only was Voc increased, but Jsc was also enhanced. We observed that the double-N doped sample forms a new microstructure with more mesopores, which enhance the transfer of electrolyte. Because these mesopores are the combination core of generated electrons and holes, they need to be kept in delicate balance. When urea is brought in as the double-N dopant, the doped amount of N atoms was improved. As a result, η is increased to 7.58%, a 14% improvement compared with single-N doped TiO2.

Preparation of dye-sensitized solar cells with high photocurrent and photovoltage by using mesoporous titanium dioxide particles as photoanode material

Several mesoporous TiO2 (MT) materials were synthesized under different conditions following a hydrothermal procedure using poly(ethylene-glycol)-block-poly(propylene-glycol)-block-poly(ethylene-glycol) (P123) as the template and titanium isopropoxide as the titanium source. The molar ratios of Ti/P123, and the pH values of the reaction solution in an autoclave were investigated. Various techniques such as Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), laser Raman spectrometry (LRS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the products. Then, these materials were assembled into dye-sensitized solar cells (DSSCs). Analysis of the J–V curves and electrochemical impedance spectroscopy (EIS) were applied to characterize the cells. The results indicated that the specific surface area and crystalline structure of these materials provide the possibility of high photocurrent for the cells, and that the structural characteristics of the specimens led to increased electron transfer resistance of the cells, which was beneficial for the improvement of the photovoltage of the DSSCs. The highest photoelectric conversion efficiency of the cells involving MT materials reached 8.33%, which, compared with that of P25-based solar cell (5.88%), increased by 41.7%.

Improved performance of dye-sensitized solar cells based on modified kaolin/PVDF-HFP composite gel electrolytes

Dye-sensitized solar cells (DSSCs) fabricated with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) composite gel electrolytes containing variable amounts of modified kaolin were studied in this work. The kaolin was modified with silane coupling agent γ-aminopropyltriethoxysilane (KH550), and the modified kaolin (M-KL) was characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The results of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) indicated that the crystallinity of polymer membranes decreased with the addition of M-KL nanoparticles. The ionic conductivity and diffusion coefficient (I3−) of polymer gel electrolytes (PGEs) reached optimum values of 9.452 × 10−3 S cm−1 and 10.37 × 10−6 cm2 s−1 for 3 wt% M-KL, respectively, which contributed to higher short-circuit current density (Jsc) and photoelectric conversion efficiency (η) of the corresponding DSSCs. The optimum level of η reached 7.48% under the illumination of 100 mW cm−2, an increase of 16.3% compared with the DSSC without M-KL.

Multi-functional 3D N-doped TiO 2 microspheres used as scattering layers for dye-sensitized solar cells

Three-dimensional TiO2 microspheres doped with N were synthesized by a simple single-step solvothermal method and the sample treated for 15 h (hereafter called TMF) was then used as scattering layers in the photoanodes of dye-sensitized solar cells (DSSCs). The TMF was characterized using scanning electron microscopy, high resolution transmission electron microscopy, Brunauer-Emmett-Teller measurements, X-ray diffraction, and X-ray photoelectron spectroscopy. The TMF had a high surface area of 93.2 m2∙g–1 which was beneficial for more dye-loading. Five photoanode films with different internal structures were fabricated by printing different numbers of TMF scattering layers on fluorine-doped tin oxide glass. UV-vis diffuse reflection spectra, incident photon-to-current efficiencies, photocurrent-voltage curves and electrochemical impedance spectroscopy were used to investigate the optical and electrochemical properties of these photoanodes in DSSCs. The presence of nitrogen in the TMF changed the TMF microstructure, which led to a higher open circuit voltage and a longer electron lifetime. In addition, the presence of the nitrogen significantly improved the light utilization and photocurrent. The highest photoelectric conversion efficiency achieved was 8.08%, which is much higher than that derived from typical P25 nanoparticles (6.52%).

Preparation of electrophoretic nanoparticles for electronic paper

C.I. Pigment Red 48 : 2 (P.R.48 : 2) and C.I. Pigment Red 57 : 1 (P.R.57 : 1) composite particles encapsulated with three kinds of polyethylene (PE), which had different molecular chain structure, were prepared by dispersion polymerisation method. The modified pigments were characterised by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), UV–Vis spectroscopy and chroma. The modified particles were dispersed in Isopar L : C2Cl4 = 1 : 1 and then successfully incorporated in an electrophoretic display cell, and P.R.48 : 2/high-density polyethylene (HDPE) particles, which had electron-withdrawing groups and coating materials with high crystallinity and without short-chain branches, had the best properties and their highest contrast ratio on the same device was found to be 2.67, which was better than those of pigments modified with others PE.

A novel amphiphilic fluorescent probe BODIPY–O-CMC–cRGD as a biomarker and nanoparticle vector

Fluorescent probes have been demonstrated to be promising candidates as biomarkers and biological carriers. Our study focuses on the development of a novel amphiphilic fluorescent probe with good photostability, high water solubility, excellent specificity and promising loading capability for tumor diagnosis and treatment. At first, BODIPY dye and O-carboxymethyl chitosan were prepared via a chemical reaction. Then, the prepared BODIPY dye and cRGD were bonded to O-carboxymethyl chitosan successively via an acylation reaction. Finally, we obtained the desired amphiphilic fluorescent probe: BODIPY–O-CMC–cRGD, which was based on the fluorescence resonance energy transfer (FRET) principle for selective visualization of tumors in vitro. Through a series of experiments, we found that this fluorescent probe possessed better fluorescence characteristics and tumor targeting properties. Simultaneously, by self-assembly, the amphiphilic probe encapsulated the other flexible structure of BODIPY2 and the rigid structure of porphyrin, which formed distinct nanoparticles with different particle sizes. Hence, we could observe different phagocytosis processes of the two nanoparticles in the tumor cells via the fluorescence of dyes by confocal laser scanning microscopy. Therefore, the results suggest that the fluorescent probe has advantages in tumor detection, and the constructed tumor-specific nanoparticles show high clinical potential to be utilized not only in visual and precise diagnosis but also in excellent drug delivery for tumor treatment. Henceforth, we will prepare new targeted and visualized pharmaceuticals by replacing BODIPY2 and porphyrin with antineoplastic drugs for future tumor treatment.

The self-assembly of monosubstituted BODIPY and HFBI-RGD

A novel fluorescent probe was constructed by the self-assembly of monosubstituted BODIPY and a novel targeted hydrophobin named hereafter as HFBI-RGD. Optical measurements and theoretical calculations confirmed that the spectral properties of the probe were greatly influenced by the BODIPY structure, the appropriate volume of BODIPY and the cavity of HFBI-RGD. The experiments in vivo and ex vivo demonstrated that the probe had excellent ability for tumor labelling.